Solar Cycle 24 Begins

Jan.
10, 2008: Hang on to your cell phone, a new solar
cycle has just begun.

"On
January 4, 2008, a reversed-polarity sunspot appeared—and
this signals the start of Solar Cycle 24," says David
Hathaway of the Marshall Space Flight Center.

Above:
Images of the first sunspot of Solar Cycle 24 taken by the
NASA/ESA Solar and Heliospheric Observatory (SOHO). [Larger
image] [Movie]

Solar
activity waxes and wanes in 11-year cycles. Lately, we've
been experiencing the low ebb, "very few flares, sunspots,
or activity of any kind," says Hathaway. "Solar
minimum is upon us."

The
previous solar cycle, Solar Cycle 23, peaked in 2000-2002
with many furious solar storms. That cycle decayed as usual
to the present quiet leaving solar physicists little to do
other than wonder, when would the next cycle begin?

The
sunspot that appeared on January 4th fits both these criteria.
It was high latitude (30 degrees N) and magnetically reversed.
NOAA named the spot AR10981, or "sunspot 981" for
short.

Sunspot
981 was small--only about as wide as Earth, which counts as
small on the grand scale of the sun--and it has already faded
away. But its three day appearance on Jan. 4-6 was enough
to convince most solar physicists that Solar Cycle 24 is underway.

Doug
Biesecker of NOAA's Space Weather Prediction Center in Boulder,
Colorado, likens sunspot 981 "to the first robin of spring.
There's still snow on the ground, but the seasons are changing."
Last year, Biesecker chaired the Solar Cycle 24 Prediction
Panel, an international group of experts from many universities
and government agencies. "We predicted
that Solar Cycle 24 would begin around March 2008 and it looks
like we weren't far off," he says.

Right:
The first auroras of the new solar cycle, photographed Jan.
4, 2008, by Calvin Hall of Palmer, Alaska. [more]

The
onset of a new solar cycle is significant because of our increasingly
space-based technological society.

"Solar
storms can disable satellites that we depend on for weather
forecasts and GPS navigation," says Hathaway. Radio bursts
from solar flares can directly interfere with cell phone reception
while coronal mass ejections (CMEs) hitting Earth can cause
electrical power outages. "The most famous example is
the Quebec outage of 1989, which left some Canadians without
power for as much as six days."

Air
travel can be affected, too.

Every
year, intercontinental flights carry thousands of passengers
over Earth’s poles. It's the shortest distance between, say,
New York and Tokyo or Beijing and Chicago. In 1999, United
Airlines made just twelve trips over the Arctic. By 2005,
the number of flights had ballooned to 1,402. Other airlines
report similar growth.

"Solar
storms have a big effect on polar regions of our planet,"
says Steve Hill of the Space Weather Prediction Center. "When
airplanes fly over the poles during solar storms, they can
experience radio blackouts, navigation errors and computer
reboots all caused by space radiation." Avoiding the
poles during solar storms solves the problem, but it costs
extra time, money and fuel to "take the long way around."

Above:
An increasing number of international business flights cross
Earth's Arctic to save time, fuel and money. [Larger
image]

Now
for the good news: More solar storms also means more auroras—"the
greatest show on Earth." During the last solar maximum,
Northern Lights were spotted as far south as Arizona, Florida
and California. Not so long ago, only visitors to the Arctic
regularly enjoyed auroras, but with increasing attention to
space weather and constantly improving forecasts, millions
of people at all latitudes will know when to go out and look.

Much
of this is still years away. "Intense solar activity
won't begin immediately," notes Hathaway. "Solar
cycles usually take a few years to build from solar minimum
(where we are now) to Solar Max, expected in 2011 or 2012."

Strange
but True: While Solar Cycle 24 has begun, Solar
Cycle 23 has not ended. Both cycles will coexist for
a period of time, perhaps a year or more, as one dies
down and the other comes to life. In the months ahead
we may see old-cycle sunspots and new-cycle sunspots
on the sun at the same time.

NASA
is gearing up to study the active sun during
Cycle 24 with the launch of a new spacecraft, the Solar
Dynamics Observatory. "SDO is a very special
observatory," says project scientist Dean Pesnell
at NASA's Goddard Space Flight Center, Greenbelt, Md.
"Using a technique called helioseismic imaging,
the spacecraft will be able to look inside the sun where
solar activity begins. SDO will join SOHO, STEREO, Hinode
and other missions already in orbit to improve our understanding
of solar storms and lay the groundwork for better space
weather forecasts."